For official plugins and theme components (and themes, eventually) you can create a dedicated topic in the proper category with the appropriate tag, or post in the topic itself. Both are fine. Though if you post your issue in the plugin/theme component topic you may find it gets to split off into a new topic to keep things organised and findable (it’s great for things like Related Topics, etc too).
I’ve updated a chunk of theme component topics with the info like the official plugin ones already have, but I haven’t done all of them yet - and I’ve also been splitting the existing ones up too. As you can imagine, it’s a bit of a chore so it’s going to take me awhile to work through them all.
The official tag is only used on the main plugin/theme/theme component topic itself, not on the peripheral ones. So if you find a bug with solved it would only get the solved tag and not the official one as well (it cuts down on the noise when you want to look at a list of all of our official customisations).
I can fervently wish for this. It is pretty slow-going a lot of the time, especially fitting it in to all the other things that need doing. Having a magic button that would do it all for me would be excellent.